Scientific publications, therapeutic breakthroughs and cultural endorsements suggest that the historical reputation of psychedelics — such as lysergic acid diethylamide (LSD), mescaline (from the peyote cactus) and psilocybin (mushrooms) — as dangerous or inherently risky have unfairly overshadowed a more optimistic interpretation.

Recent publications, like Michael Pollan’s How to Change your Mind, showcase the creative and potentially therapeutic benefits that psychedelics have to offer — for mental health challenges like depression and addiction, in palliative care settings and for personal development.

I am a medical historian, exploring why we now think that psychedelics may have a valuable role to play in human psychology, and why over 50 years ago, during the heyday of psychedelic research, we rejected that hypothesis. What has changed? What did we miss before? Is this merely a flashback?

In this April 2010 photo, one gram of psilocybin is seen on a scale at New York University, where a study investigated the effects of hallucinogenic drugs on the emotional and psychological state of advanced cancer patients.(AP Photo/Seth Wenig)

In 2017, Oakland, Calif., hosted the largest gathering to date of psychedelic scientists and researchers. Boasting attendance of more than 3,000 participants, Psychedelic Science 2017 brought together researchers and practitioners with a diverse set of interests in reviving psychedelics — from filmmakers to neuroscientists, journalists, psychiatrists, artists, policy advisers, comedians, historians, anthropologists, Indigenous healers and patients.

Measuring reaction, not experience

As a historian, however, I am trained to be cynical about trends that claim to be new or innovative. We learn that often we culturally tend to forget the past, or ignore the parts of the past that seem beyond our borders.

For that reason, I am particularly interested in understanding the so-called psychedelic renaissance and what makes it different from the psychedelic heyday of the 1950s and 1960s.

The historic trials were conducted at the very early stages of the pharmacological revolution, which ushered in new methods for evaluating efficacy and safety, culminating in the randomized controlled trial (RCT). Prior to standardizing that approach, however, most pharmacological experiments relied on case reports and data accumulation that did not necessarily involve blinded or comparative techniques.

Shaman Pablo Flores pours ayahuasca into a plastic cup during a sacred ceremony in the Peruvian Jungle in May 2018.(AP Photo/Martin Mejia)

Historically, scientists were keen to separate pharmacological substances from their organic cultural, spiritual and healing contexts — the RCT is a classic representation of our attempts to measure reaction rather than to interpret experience. Isolating the drug from an associated ritual might have more readily conveyed an image of progress, or a more genuine scientific approach.

Rethinking the scientific method

Modern science has focused attention on data accrual — measuring reactions, identifying neural networks and discovering neuro-chemical pathways. It has moved decidedly away from larger philosophical questions of how we think, or what is human consciousness or how human thoughts are evolving.

We may now have more sophisticated tools for advancing the science of psychedelics. But psychedelics have always inspired harmony between brain and behaviour, individuals and their environments, and an appreciation for western and non-western traditions mutually informing the human experience.

In other words, scientific pursuits need to be coupled with a humanist tradition — to highlight not just how psychedelics work, but why that matters.